Multilevel Non-Inverting Buck-Boost Converter with Low-Frequency Ripple-Shaping Based Controller for Operating in Step-down/Step-up Transition Region

This paper introduces a multilevel non-inverting buck-boost (ML-NIBB) converter and a complementary mixed-signal controller as an alternative to the conventional non-inverting buck-boost (NIBB) based switch-mode power supply (SMPS) solutions. This ML-NIBB is essentially a series connection of a 3-level flying capacitor (FC) buck converter and a 3-level FC boost converter with a shared inductor between the two stages. This new topology offers an advantage of increased power density compare to NIBB, through simultaneous reduction of the volume and improvements in power processing efficiency. The converter operates in 3-level buck mode or 3-level boost mode according to the input voltage. In addition, the multi-level ripple-shaping mode is introduced to provide a smooth transition between the two modes. The advantages of the new topology are experimentally verified, through a comparison with a conventional solution operating with a 1.8 V to 10 V input, 3.3 V to 10 V/30 W output experimental prototype. The introduced ML-NIBB based solution demonstrates higher efficiency among all three operating modes and up to 20% efficiency improvements in light load while using 2.2 times smaller inductor. Also, the effectiveness of extended version of the ripple-shaping controller is verified on the same prototype.